The use of platinum II complexes as a catalyst for hydroformylation (OXO reaction) is known. Thus, for example, PtH(SnCl .sub.3)(PPh.sub.3).sub.2 are shown by Hsu and Orchin, J. Amer. Chem Soc., 97 353 (1975)to be useful for conversion of 1-pentene to aldehydes. Schwager and Knifton, J. Cat. 45, 256 (1976), U.S. Pat. No. 3,981,925 and U.S. Pat. No. 3,996,293 disclose use of PtCl.sub.2 (PPh.sub.3).sub.2 +SnCl .sub.2 for a similar reaction with 1-heptene. Kawabata, et al., J.C.S. Chem. Comm 462 (1979) teach Pt(PhCN).sub.2 Cl.sub.2 +Ph.sub.2 P(CH.sub.2).sub.x PPh.sub.2 for conversion of 1-pentene to aldehydes. U.S. Pat. Nos. 4,101,565 and 4,155,939 show the dimer (PtCl.sub.2 PPh.sub.3).sub.2 +SnCl.sub.2 for hydroformylation of 1-hexene. U.S. 3,876,672 also shows hydroformylation of 1-hexene with PtH(PPh.sub.3).sub.3.sup.30 HSO.sub.4.sup.-.
In the hydroformylation reaction of olefin with such catalysts the reaction proceeds as follows: ##STR1##
In such reactions, usually greater than 90% selectivity (relative to total aldehydes) to linear aldehydes is obtained when a platinum complex is employed as a catalyst. However, when propylene is the olefin, lower yield and selectivity to linear aldehyde (n-butyraldehyde) is obtained and this is shown by the work of Knifton and his associates referred to above it is to be understood that with a chemical commodity such as n-butyraldehyde, even a small increase in selectivity to the desired linear product is highly desirable because of the large volumes processed. This invention provides a novel catalyst which gives improved selectivity and yield to linear aldehydes particularly for n-butyraldehyde and thus makes a significant advance in the art.